Compact, high-resolution spectrometers with grating–metasurface coupling for CO2 detection

Abstract

Off-axis reflective optical systems are commonly used to minimize the dimensions of spectrometers. However, despite sophisticated off-axis reflective designs, constructing systems with excellent spectral and spatial resolutions, particularly those that can be used for CO2 gas detection in space-based spectrometers, necessitates maintaining a significant overall instrument size. The metasurface is an innovative optical device that can enable spectrometer miniaturization. For CO2 spectral detection in the near-infrared spectral range of 1590–1620 nm, this study proposes a device that integrates a grating with a metasurface for off-axis convergence within the relevant wavelength range. The grating facilitates primary spectral dispersion, whereas the metasurface enables off-axis convergence at different wavelengths. Grating–metasurface coupling effectively enhances the spectral resolution of the spectrometer, mitigating any efficiency losses caused by excessive off-axis angles. The proposed strategy exhibits high potential for on-chip integrated photonics and the fabrication of small-size spaceborne spectrometers.